Effect of damage on mechanical behavior of HDPE geomembrane

For investigation of the failure mechanism of the HDPE geomembrane on the slope of a newly constructed landfill, which is related to a series of small boreholes during the construction, tensile tests and geotechnical centrifuge model tests are carried out on the intact and damaged HDPE geomembranes as well as their simulants. Four kinds of damages to the HDPE geomembrane are simulated by folding of the membranes, drilling of holes through the membranes, and combination of boreholes and defects remaining on the edge of the samples. It is found from the tensile tests that, when the tension load of the damaged geomembrane reaches its ultimate value, the load drops abruptly, and that the development of the tension strain concentrates in damaged parts. As a result, the ultimate ratio of elongation of the damaged HDPE geomembrane is much less than that of the intact HDPE geomembrane, only about one-tenth. Two preliminary centrifuge tests show that, under the large MSW settlement condition, holes on the simulant geomembrane at the top of the slope move a certain distance from their original positions downward the lined slope, their diameters enlarge twice, and silicone glue begins to be detached from the geomembrane, registering an impending rupture of the damaged geomembrane.